Input devices allow data and instructions to enter a computer. Common input devices include keyboards, mice, joysticks, light pens, trackballs, scanners, digitizers, microphones, magnetic ink card readers, optical character readers, bar code readers, and optical mark readers. Output devices send data from the computer to the user or another device. Common output devices are monitors, printers like laser and inkjet printers, plotters, sound cards, and screens.

1. input devices

2. definition
• A component or peripheral device (such as a
barcode reader, graphic tablet, keyboard,
magnetic-stripe reader, modem, mouse,
scanner, or stylus) that feeds data or instruction
into a computer for display, processing, storage,
or outputting or transmission.

3. Keyboard
• Keyboard is the most common and very popular
input device which helps in inputting data to the
computer. The layout of the keyboard is like that
of traditional typewriter, although there are some
additional keys provided for performing
additional functions.
• Keyboards are of two sizes 84 keys or 101/102
keys, but now keyboards with 104 keys or 108
keys are also available for Windows and
Internet.

4. Mouse
• Mouse is most popular pointing device. It is a
very famous cursor-control device having a
small palm size box with a round ball at its base
which senses the movement of mouse and
sends corresponding signals to CPU when the
mouse buttons are pressed.
• Generally it has two buttons called left and right
button and a wheel is present between the
buttons. Mouse can be used to control the
position of cursor on screen, but it cannot be
used to enter text into the computer.

5. Joystick
• Joystick is also a pointing device which is used
to move cursor position on a monitor screen. It is
a stick having a spherical ball at its both lower
and upper ends. The lower spherical ball moves
in a socket. The joystick can be moved in all four
directions.
• The function of joystick is similar to that of a
mouse. It is mainly used in Computer Aided
Designing(CAD) and playing computer games.

7. Light Pen
• Light pen is a pointing device which is
similar to a pen. It is used to select a
displayed menu item or draw pictures on
the monitor screen. It consists of a
photocell and an optical system placed in
a small tube. When the tip of a light pen is
moved over the monitor screen and pen
button is pressed, its photocell sensing
element detects the screen location and
sends the corresponding signal to the
CPU.

9. Track Ball
• Track ball is an input device that is mostly
used in notebook or laptop computer,
instead of a mouse. This is a ball which is
half inserted and by moving fingers on
ball, pointer can be moved. Since the
whole device is not moved, a track ball
requires less space than a mouse. A track
ball comes in various shapes like a ball, a
button and a square.

11. Scanner
• Scanner is an input device which works
more like a photocopy machine. It is used
when some information is available on a
paper and it is to be transferred to the
hard disc of the computer for further
manipulation. Scanner captures images
from the source which are then converted
into the digital form that can be stored on
the disc. These images can be edited
before they are printed.

13. Digitizer
• Digitizer is an input device which converts
analog information into digital form. Digitizer can
convert a signal from the television or camera
into a series of numbers that could be stored in
a computer. They can be used by the computer
to create a picture of whatever the camera had
been pointed at. Digitizer is also known as
Tablet or Graphics Tablet because it converts
graphics and pictorial data into binary inputs. A
graphic tablet as digitizer is used for doing fine
works of drawing and image manipulation
applications.

15. Microphone
• Microphone is an input device to input
sound that is then stored in digital form.
The microphone is used for various
applications like adding sound to a
multimedia presentation or for mixing
music.

16. Magnetic Ink Card Reader(MICR)
• MICR input device is generally used in
banks because of a large number of
cheques to be processed every day. The
bank's code number and cheque number
are printed on the cheques with a special
type of ink that contains particles of
magnetic material that are machine
readable. This reading process is called
Magnetic Ink Character Recognition
(MICR). The main advantages of MICR is
that it is fast and less error prone.

18. Optical Character Reader(OCR)
• OCR is an input device used to read a
printed text. OCR scans text optically
character by character, converts them into
a machine readable code and stores the
text on the system memory.

20. Bar Code Readers
• Bar Code Reader is a device used for
reading bar coded data (data in form of
light and dark lines). Bar coded data is
generally used in labelling goods,
numbering the books etc. It may be a
hand held scanner or may be embedded
in a stationary scanner. Bar Code Reader
scans a bar code image, converts it into
an alphanumeric value which is then fed to
the computer to which bar code reader is
connected.

22. Optical Mark Reader(OMR)
• OMR is a special type of optical scanner
used to recognize the type of mark made
by pen or pencil. It is used where one out
of a few alternatives is to be selected and
marked. It is specially used for checking
the answer sheets of examinations having
multiple choice questions.

24. Out Put devices

25. Definition
• An output device is any device used to
send data from a computer to another
device or user. Most computer data output
that is meant for humans is in the form of
audio or video. Thus, most output devices
used by humans are in these categories.
Examples include monitors, projectors,
speakers, headphones.

26. Printers
• Computers were supposed to bring about
the dream of a 'paperless office'. This now
looks very unlikely to happen because
paper has got some advantages over
computers when looking at information.

27. Laser Printer
• This type of printer is the main one used in
schools, offices and industry because it
produces high-quality printouts very
quickly, with good resolution.

28. Inkjet Printers
• :Basic models of this type of printer are
cheap to buy, and let you print in colour.
• The quality of the best inkjet's can be very
high and can be used for photographs

30. Plotters
• Plotters are large printer type devices. Instead of
using ink cartridges, plotters use pens to draw
the output on to paper. With different coloured
pens, plotters can produce colour output.
• Plotters are capable of producing very accurate
drawings and plans. They are most often used in
computer aided design (CAD).
•

32. Sound Card
• A sound card captures sounds and
changes them into digital binary numbers
that are stored as files in your computer.

33. Screens and Mointors
• Screens are the most common of output
devices. They show what's going in the
computer. There are really three main types.
• ibook transparent screen
• Liquid Crystal Display (LCD) Screens.
• Thin Film Transistor (TFT) Screens.
• Cathode Ray Tube (CRT) Screens
•